{"id":"CVE-2026-41161","aliases":["GHSA-43fj-qp3h-hrh5"],"url":"https://o3.security/vulnerability/CVE-2026-41161","summary":"Username Enumeration via Timing Attack","details":"### Summary\nThe `/api/auth/login` endpoint contains a logic flaw that allows unauthenticated remote attackers to enumerate valid usernames by measuring the application's response time.\n\n### Details\nThe logic flaw can be located at the below point in source:\nhttps://github.com/Sync-in/server/blob/7868bb2b3025f92e6c38087456304758713971b2/backend/src/applications/users/services/users-queries.service.ts#L91-L95\n\nEndpoints used for authentication should respond to the user with a consistent cadence, preventing remote actors from deriving sensitive information about an application based on backend behavior. In the case of authentication endpoints, this timing discrepancy is often caused by short-circuiting due to the lack of a matched user to compare against - as is the case with Sync-in.\n\n### Validation\nTickTock Enum (Burp Suite Extension) was utilized to validate this finding. Authentication attempts with a valid username see a response from the application at around 350-400ms on average, while invalid usernames are returned at only 95-100ms on average.\n<img width=\"1302\" height=\"284\" alt=\"image\" src=\"https://github.com/user-attachments/assets/31eeb72a-c3c2-4057-ac69-c0c92f0bbd4e\" />\n\n### Impact\nAn unauthenticated remote attacker can enumerate valid usernames. This significantly weakens the application's security posture by facilitating targeted brute-force attacks, stuffing, social engineering, and a suite of other more targeted attacks.","published":"2026-05-08T13:00:54.485Z","modified":"2026-08-12T03:51:39.346753586Z","cvss":null,"epss":{"score":0.00333,"percentile":0.25851,"asOf":"2026-08-08"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@sync-in/server","fixedVersion":"2.2.0"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/Sync-in/server/releases/tag/v2.2.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41161.json"},{"type":"ADVISORY","url":"https://github.com/Sync-in/server/security/advisories/GHSA-43fj-qp3h-hrh5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41161"},{"type":"PACKAGE","url":"https://github.com/Sync-in/server"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:39.346753586Z"}}